GHOST instrument is being developed for the Gemini telescope and is a collaboration between AAO, the Herzberg Astronomy and Astrophysics (HAA) in Canada and the Australian National University (ANU). The instrument is a fiber fed spectrograph with R<50,000 in two-object mode and R<75,000 in single object mode. This paper presents mechanical design and optical alignment of the lens barrels used for the two cameras in the instrument. A divide and conquer approach was used. Camera lenses were aligned to their respective individual cells for the tilt and axial spacing, and then bonded to flexures for stability. Centering of the lens to each other was done as the individual cells were stacked into barrels. Alignment in tilt and axial position was performed on Laser Alignment and Assembly Station (LAS) manufactured by Opto-Alignment Technology, Inc. Design of the individual optical cells provides low-stress restraint and at the same time ensures high rigidity and long-term mechanical stability of the mount.
|